The image forming apparatus, employing the electro-photographic method, is an apparatus which forms a toner image by an electrical charge, subsequent exposure and development, and then transfers the formed image onto a recording member as a permanent image.
Since dried toner particles are used in the image forming apparatus employing the electro-photographic method, various problems occur due to dust, such as loosened toner particles, paper-sheet powder, and particles generated by electrical discharge.
Among various dusts in the apparatus, dust on an exposure section directly results in lower image quality, leading to various technologies being developed to prevent the exposure section from creating such dust.
Unexamined Japanese Patent Application Publication No. 6-317951 discloses that an aperture to introduce light rays is formed at the top of a frame, mounted on a laser emitting section of a laser exposure device, to support a dustproof glass, and that members positioned more upstream in the moving direction of a photoconductor are placed higher than members positioned more downstream in the moving direction of the photoconductor, so that air is prevented from flowing toward dustproof glass, whereby the particles, such as spattered toner, are prevented from landing on dustproof glass.
Unexamined Japanese Patent Application Publication No. 2000-258968 discloses an image forming apparatus in that an air regulating member to control airflows is mounted upstream of an exposure position in the moving direction of a photoconductor.
Unexamined Japanese Patent Application Publication No. 2003-054024 discloses an image forming apparatus in that a cover is provided which protrudes from the top of an LED head toward the upstream in the moving direction of the photoconductor, and said cover is declined to come close to the photoconductor toward the LED head.
Dustproofing members, disclosed in the above patent documents, effectively prevent dust from landing on the exposure device, however they are not effective to counter dust which has landed and accumulated on dustproofing members themselves. The above documents do not address this problem.
Most of the image forming apparatuses are structured so that their interior can be opened for maintenance or changing components of the photoconductor, as well as a charging device, an exposure device, a developing device, and a cleaning device, all being arranged around the photoconductor. As shown by the dashed lines in FIG. 2, some image forming apparatus are structured so that the photoconductor opens when the upper section is moved upward.
Since a laser-ray exposure device, being a complex structure, occupies much space in the image forming apparatus, said exposure device is mounted on the skeleton structure of the image forming apparatus. When the interior of the apparatus is open, most of the laser-ray exposure devices are not structured of movable sections.
On the other hand, when an LED (being a light emitting diode) exposure device is used in the image forming apparatus, said LED exposure device is preferably structured to be open by a cover.
In the above patent documents, dustproofing members are open with the exposure device, but the landed dust on dustproofing members drops onto the exposure device, whereby the exposure device becomes dusty, which is a major problem.
In order to clean the exposure device, long laborious hours are required.